High Pressure Phase Behavior of the Homologous Series CO₂ + 1-Alcohols

Abstract

The phase behavior of the supercritical CO 2 + 1-alcohol homologous series for 1-octanol and higher alcohols is investigated. A literature survey revealed that sufficient data are available lower alcohols (1-decanol and lower) but data are limited for higher 1-alcohols. Data for CO 2 + 1-dodecanol, CO 2 + 1-tetradecanol, and CO 2 +1-hexadecanol were thus measured using a visual static synthetic method for T = 313− 353 K. Measured and literature data indicated that the phase transition pressures are very high (>28 MPa) for CO 2 + 1decanol and higher alcohols in the mixture critical region. Additionally, a temperature inversion (increasing temperature leading to decreasing phase transition pressure) is present in the mixture critical region and is more pronounced in systems containing higher 1-alcohols. The temperature inversion is postulated to result from the formation of alcohol multimers due to hydrogen bonding between alcohol molecules. From the phase behavior data as well as published upper critical end point and solid−liquid−liquid−vapor equilibria data, Type III phase behavior according to the classification of Scott and van Konynenburg is assigned to the systems CO 2 + 1-octanol to CO 2 + 1tetradecanol. However, for higher alcohols additional investigations are required to assign a phase behavior type. This systematic study hopes to aid future thermodynamic modeling attempts to describe the complex phase behavior of CO 2 + 1-alcohol systems.

High-Pressure Phase Equilibria Measurements of the Carbon Dioxide + Cycloheptane Binary System

“…The isothermal curves (P, 𝑥 𝐶𝑂 2 ) thus cannot be graphed directly from the measured data presented in Table 2. Interpolated values were calculated using second order polynomials to describe the pressuretemperature relationship of the raw experimental data at constant composition, following the reliable method previously described in detail by Schwarz et al 6,[19][20][21] The following second order polynomial was used…”

High Pressure Vapor–Liquid Equilibrium Data for the Quaternary Carbon Dioxide + 1-Decanol + 3,7-Dimethyl-1-octanol + n-Dodecane System

“…The presence of a temperature inversion is, therefore, noted if there is a region where the solubility of a system increases with an increase in temperature. According to the literature, ,− temperature inversions are a common occurrence for CO 2 + 1-alcohol systems. When evaluating the VLE data for mixture 1, presented in Table , it reveals that as temperature increases from 308 to 328 K at a constant pressure of 17 MPa, the mutual solubility increases, that is, the amount of CO 2 in the liquid phase increases and the total amount of solute decreases, while in the vapor phase, the amount of CO 2 decreases and the total amount of solute increases.…”